Need Some Help Figuring out a Trapazoid Image on a G07 Monitor

rmackie6661

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Need Some Help Figuring out a Trapazoid Image on a G07 Monitor

Hey everyone I have a Rebuild GO7 that is giving me a trapezoid image. it's curved outward on all four corners. I just cant seem to figure this one out. looking for some help.
Here's what I've tried with no luck

Different tube
New Caps, Flyback, IC chip, Filter cap, T501, T503, L503, HOT, Power Reg, R908, Reflowed trace pads all over the bottom, Hor coil, top right cylinder part.

Voltages are at 119.6 B+
I've tried all the adjustment combos I can think of but nothing gets it fully out

Any ideas out there???
 

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have you tried a different pcb to see if the problem still exists?

I'm curious if you go into test mode and pull up the cross-hatch pattern if it looks the same.
 
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I'll check the Cap rating
Yeah it doesn't matter which PCB I put in it's the same.

I believe the cap would have been. 470uf x 25v 105'

the g07 doesn't have any 470uf caps on it.

though I have seen someone drop a 470uf cap into C517 before but they left C518 empty. 470uf I supposed could be close to the combination of 100uf in 517 and 220uf in 518, but what if that 470 measures out at 515uf or something like that (within the 10% tolerance?)

I personally have always corrected this by using the prescribed 100uf cap in C517 and 220uf cap in C518.

I've seen guys mention on here using a 220uf in both C517 and C518, but I have not tried that nor do I know the reason they would do that.
 
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the g07 doesn't have any 470uf caps on it.

though I have seen someone drop a 470uf cap into C517 before but they left C518 empty. 470uf I supposed could be close to the combination of 100uf in 517 and 220uf in 518, but what if that 470 measures out at 515uf or something like that (within the 10% tolerance?)

I personally have always corrected this by using the prescribed 100uf cap in C517 and 220uf cap in C518.

I've seen guys mention on here using a 220uf in both C517 and C518, but I have not tried that nor do I know the reason they would do that.

I just install whatever the kit calls for. haven't had any issues so far. I have limited experience with G07s, I don't come across different ones that need fixing every 2 days like you do. lol
 
The original values of C517 and C518 were 100 uf and 220 uf respectively. Both of those capacitors are connected in parallel on the circuit board. Remember, capacitors wired in parallel ADD their values. So, 100 uf and 220 uf = 320 uf.

I have found over the years that the 320 uf capacitance value is too low to display a perfectly squared picture (or if it does, it only lasts a couple of months). For over the past 30 years, I have replaced the capacitor C517 with a 220 uf instead of using the original 100 uf value. By having both C517 AND C518 at 220 uf each, that will equal 440 uf which in my experience produces the most true and squared picture and holds that squareness for a long time.

You can replace both C517 and C518 with a single 470 uf (leave one of those capacitor locations empty), but generally the 470 uf is physically larger and may not fit next to the flyback. If the 470 uf you used didn't produce a nice squared picture, perhaps you got a bad or "marginal" one? A capacitor ESR meter will show whether it's good or not. I always test every new capacitor on my ESR meter first before installing as I've gotten some bad ones right out of the package.
 
changed out the C517 and 518 caps and checked the whole area over and all of it looks good. also changed out the B+ pot it looked a bit rusty and was loose but still the same issue. Ughhhhhh
Any other ideas.
Great pic but that stupid hourglass shape to it.
 
have you tried scrolling the image all the way out (wide) with the horizontal width coil to see what it looks like?

I assume you've messed with the horizontal frequency pot as well?
 
If you want to increase the range of the width coil, you change the value of the width range capacitor, C515. The factory default value of it is .53 uf @ 400 volts and it's a Metalized PolyPropylene type because it's such a hard working capacitor (ordinary capacitors will fail in minutes if not immediately). You can try up or down in value a step or two in capacitance.

Bob Roberts sells a width cap kit. From .53 uf, the steps are usually, .47 and .39 or .56 and .68
 
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i also make a width cap kit with many more caps and values than BR kit and all my caps are nichicon or panasonic 105c and all of mine are 5% tolerance not the 10% like in other kits. my site is open and taking orders and shipping the same day on almost everything.
 
tried the all the adjustment pots. and no luck it's just not adjusting at all. I've never seen this for the hundreds of G0's I've worked on over the years.
 
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